The primary goal of this proposal is to systematically examine the psychological and physiological responses of narcotic addicts to stimuli previously associated with drug-taking behavior. Drug addicts and non-addicted control subjects will be shown stimuli reminiscent of drug-taking behavior in the form of a videotape (VT) or an assortment of drug paraphernalia. Prior to the stimulus presentation, measures of mood state and craving will be taken. During the presentation, physiological measures of heart rate, skin resistance, skin temperature and respiration will be monitored along with subjective level of craving. Subsequent to the VT, the psychological measures will again be taken and compared to the pre-stimulus scores. A five minute VT will be made of the subject before and after the experiment and scored by raters for signs and symptoms such as eye tearing, rhinorrhea, ptosis, yawning, sniffing and signs of irritability which might indicate either a conditioned withdrawal or a conditioned "high". The same measures will also be taken before, during and after viewing control films, including a non-drug related emotionally neutral film and a non-drug related stress film as controls for general arousal and stress factors. Due to the high degree of lability found in the autonomic responses of drug addicts, an initial study will be undertaken to measure these responses, as well as the psychological responses. The goal will be an assessment of the response systems' stability during a session in which emotionally neutral stimuli are presented. Also to be studied is the response reliability from one session to another--two days later. In subsequent studies we will attempt to answer the following questions: 1) Are the subjects' responses specific to drug-related stimuli? 2) Are the responses limited to addicts, i.e., those with conditioning experiences--or at least, is the response topography different from control groups? 3) Are the responses greater in subjects who have been addicted longer--thus having a longer conditioning history?